Systems and methods for viewing medical 3D imaging volumes

ABSTRACT

A method of automatically tracking the portions of a 3D medical imaging volume, such as the voxels, that have already been displayed according to use-defined display parameters, notating those portions, and providing the user with information indicating what portions of the imaging volume have been displayed at full resolution.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No. 14/081,225, filed Nov. 15, 2013, entitled “SYSTEMS AND METHODS FOR VIEWING MEDICAL 3D IMAGING VOLUMES,” which is a continuation of U.S. application Ser. No. 13/535,758, filed Jun. 28, 2012, entitled “SYSTEMS AND METHODS FOR VIEWING MEDICAL 3D IMAGING VOLUMES,” now U.S. Pat. No. 8,610,746, which is a continuation of U.S. application Ser. No. 13/079,597, filed Apr. 4, 2011, entitled “SYSTEMS AND METHODS FOR VIEWING MEDICAL 3D IMAGING VOLUMES,” now U.S. Pat. No. 8,217,966, which is a continuation of U.S. application Ser. No. 11/268,262, filed Nov. 3, 2005, entitled “SYSTEMS AND METHODS FOR VIEWING MEDICAL 3D IMAGING VOLUMES,” now U.S. Pat. No. 7,920,152, which claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application Ser. No. 60/625,690, filed on Nov. 4, 2004, each of which is hereby expressly incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to management and viewing of medical images and, more particularly, to systems and methods of tracking which portions of three dimensional imaging volumes have been displayed using predetermined display parameters.

Description of the Related Art

Medical imaging is increasingly moving into the digital realm. This includes imaging techniques that were traditionally analog, such as mammography, x-ray imaging, angiography, endoscopy, and pathology, where information can now be acquired directly using digital sensors, or by digitizing information that was acquired in analog form. In addition, many imaging modalities are inherently digital, such as MRI, CT, nuclear medicine, and ultrasound. Increasingly these digital images are viewed, manipulated, and interpreted using computers and related computer equipment. Accordingly, there is a need for improved systems and methods of viewing and manipulating these digital images.

For projection modalities like mammography and radiography, information may be represented in digital images in the form of a two dimensional array of pixels (picture elements). Other techniques are capable of creating cross sectional views of the body, such as magnetic resonance imaging (MRI), computed tomography (CT), and positron emission computed tomography (PET). With these techniques, the information in an image represents a two-dimensional slice of the body, with each pixel in the image representing information from a small volume in space, a voxel (volume element). In a typical imaging exam (“scan”) using these modalities, a series of parallel images are acquired through the body. The information in this series of images therefore represents a 3D volume of space or imaging volume. In addition, a three-dimensional imaging volume may be created from a set of nonparallel images as well. It is also possible to perform a three-dimensional acquisition directly with some modalities. Thus, the image volume may be generated by a device that creates a 3D data set.

While a radiologist or physician interpreting such an imaging volume might choose to view the acquired images, the plane in which the images were acquired may not be optimal for accurate and efficient analysis and interpretation of the scan. For example, imaging might be performed in the axial plane with the patient asymmetrically positioned in the scanner. The resulting images would therefore not be in the axial plane with respect to the patient's anatomy. In that case, a new set of axial images would be desired that were in the axial plane with respect to the patient's anatomy. Alternatively, structures of interest might be best evaluated in other planes, such as coronal, sagittal or oblique planes.

A reader may choose to view the information in planes that differ from the plane in which the images were originally acquired as a supplement or substitute for viewing the original images. Those of skill in the art will recognize that given the 3D imaging volume created by the original images from the imaging device, a new set of 2D images that slice up the imaging volume along other axes using multiplanar reformatting (MPR) may be created. The reformatting could be used to create a series of images in another axis prior to viewing or the viewer might choose to interactively create new views in real time as part of his analysis of the information.

No matter how the reader chooses to view the imaging volume acquired by the scan, all the acquired relevant information in the imaging volume should be viewed. Currently available systems for viewing imaging volumes do not provide a mechanism for tracking which portions of the imaging volume, such as which voxels of the imaging volume, have been displayed on a display device. Thus, the viewer must independently determine which portions of an imaging volume have been viewed. As those of skill in the art will recognize, requiring the viewer to determine when all relevant portions of an imaging volume have been viewed introduces the possibility that portions of the imaging volume are not viewed and, thus, features and/or abnormalities expressed in the unviewed portions may not be detected. Systems and methods for tracking and alerting a viewer of an imaging volume which portions of the imaging volume have been viewed are desired.

SUMMARY OF THE INVENTION

One embodiment comprises a computing system for viewing an imaging volume comprising a plurality of planar images that represent portions of an imaged object. Each of the planar images comprises a plurality of voxels. The system comprises a display device configured to display a predetermined number of pixels. The system also comprises an input interface configured to receive the imaging volume. The system also comprises an application module being configured to initiate display of one or more navigation images in one or more navigation planes. The navigation images are displayed at a reduced resolution so that the entire navigation images may be viewed on the display device. The application module is configured to initiate generation of a reformatted image comprising voxels that are along any plane determined by the user. In one embodiment, a portion of the navigation image corresponding to voxels that have been displayed at full resolution in any plane are visually distinguishable from the remaining portions of the navigation image.

Another embodiment comprises a system for viewing a three dimensional imaging volume. The system comprises: at least one three dimensional imaging volume; and a module configured to provide an interface to allow a user to selectively display portions of the imaging volume, wherein the module automatically determines whether at least a region of the three dimensional imaging volume has been displayed at a particular resolution.

Another embodiment comprises a system for viewing a three dimensional imaging volume. The system comprises: at least one three dimensional imaging volume; and means for selectively displaying portions of the image of the display, wherein the displaying means automatically determines whether at least a region of the three dimensional imaging volume has been displayed at a particular resolution.

Yet another embodiment comprises a method of viewing a 3D imaging volume on a display device coupled to a computing system. The display device is configured to concurrently display one or more navigation images and one of a plurality of reformatted images that comprise a plane of the imaging volume along any axis chosen by the view. The method comprises receiving an imaging volume at the computing system, wherein the imaging volume comprises a plurality of voxels arranged in a three dimensional array. The method also comprises displaying on the display device one or more navigation images comprising voxels of the imaging volume. The method also comprises selecting a portion of the navigation image and generating a reformatted image comprising voxels of the imaging volume from a second plane of the imaging volume. In one embodiment, the first and second planes intersect at the selected portion of the navigation image. The method also comprises displaying on the display device the reformatted image and updating the navigation image to include a visual indication that the selected portion of the navigation image has been displayed on the display device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an exemplary computing system in communication with a network and various networked devices.

FIG. 2A is a three-dimensional depiction of an imaging volume comprising a plurality of voxels.

FIG. 2B illustrates a reformatted image generated from the imaging volume of FIG. 2A.

FIG. 3A is a CT image of a patient's lumbar spine in the axial plane taken from an imaging volume comprising a plurality of axial images.

FIG. 3B is a reformatted image in the sagittal plane that was generated from the imaging volume described with respect to FIG. 3A.

FIG. 4 is a flowchart illustrating a method of tracking which voxels of a medical imaging volume have been displayed according to user-defined display parameters.

FIG. 5 illustrates portions of an exemplary graphical user interface (GUI) that may be displayed on a display device, either concurrently or separately.

FIG. 6 illustrates a display device displaying a navigation image and a reformatted image representative of a cross-section of the imaging space at the location of a navigation line on the navigation image.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Embodiments of the invention will now be described with reference to the accompanying figures, wherein like numerals refer to like elements throughout. The terminology used in the description presented herein is not intended to be interpreted in any limited or restrictive manner, simply because it is being utilized in conjunction with a detailed description of certain specific embodiments of the invention. Furthermore, embodiments of the invention may include several novel features, no single one of which is solely responsible for its desirable attributes or which is essential to practicing the inventions herein described.

FIG. 1 is a block diagram of an exemplary computing system 100 in communication with a network 160 and various network devices. The computing system 100 may be used to implement certain systems and methods described herein. The functionality provided for in the components and modules of computing system 100 may be combined into fewer components and modules or further separated into additional components and modules.

The computing system 100 includes, for example, a personal computer that is IBM, Macintosh, or Linux/Unix compatible. In one embodiment, the exemplary computing system 100 includes a central processing unit (“CPU”) 105, which may include a conventional microprocessor, an application module 145 that comprises one or more various applications that may be executed by the CPU 105. The application module 145 may include, by way of example, components, such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables.

The computing system 100 further includes a memory 130, such as random access memory (“RAM”) for temporary storage of information and a read only memory (“ROM”) for permanent storage of information, and a mass storage device 120, such as a hard drive, diskette, or optical media storage device. Typically, the modules of the computing system 100 are connected to the computer using a standards-based bus system. In different embodiments of the present invention, the standards based bus system could be Peripheral Component Interconnect (PCI), Microchannel, SCSI, Industrial Standard Architecture (ISA) and Extended ISA (EISA) architectures, for example.

The computing system 100 is generally controlled and coordinated by operating system software, such as the Windows 95, 98, NT, 2000, XP or other compatible operating systems. In Macintosh systems, the operating system may be any available operating system, such as MAC OS X. In other embodiments, the computing system 100 may be controlled by a proprietary operating system. Conventional operating systems control and schedule computer processes for execution, perform memory management, provide file system, networking, and I/O services, and provide a user interface, such as a graphical user interface (“GUI”), among other things.

The exemplary computing system 100 includes one or more of commonly available input/output (I/O) devices and interfaces 110, such as a keyboard, mouse, touchpad, and printer. In one embodiment, the I/O devices and interfaces 110 include one or more display devices, such as a monitor, that allows the visual presentation of data to a user. More particularly, display devices provide for the presentation of GUIs, application software data, and multimedia presentations, for example. In one embodiment, a GUI includes one or more display panes in which medical images may be displayed. According to the systems and methods described below, medical images may be stored on the computing system 100 or another device that is local or remote, displayed on a display device, and manipulated by the application module 145. The computing system 100 may also include one or more multimedia devices 140, such as speakers, video cards, graphics accelerators, and microphones, for example.

In the embodiment of FIG. 1, the I/O devices and interfaces 110 provide a communication interface to various external devices. In the embodiment of FIG. 1, the computing system 100 is coupled to a network 160, such as a LAN, WAN, or the Internet, for example, via a communication link 115. The network 160 may be coupled to various computing devices and/or other electronic devices. In the exemplary embodiment of FIG. 1, the network 160 is coupled to imaging devices 170, an image server 180, and a medical facility 190. In addition to the devices that are illustrated in FIG. 1, the network 160 may communicate with other computing, imaging, and storage devices.

The imaging devices 170 may be any type of device that is capable of acquiring medical images, such as an MRI, x-ray, mammography, or CT scan systems. The image server 180 includes a data store 182 that is configured to store images and data associated with images. In one embodiment, the imaging devices 170 communicate with the image server 180 via the network 160 and image information is transmitted to the image server 180 and stored in the data store 182. In one embodiment, the image data is stored in Digital Imaging and Communications in Medicine (“DICOM”) format. The complete DICOM specifications may be found on the National Electrical Manufactures Association Website at <medical.nema.org>. Also, NEMA PS 3—Digital Imaging and Communications in Medicine, 2004 ed., Global Engineering Documents, Englewood Colo., 2004, provides an overview of the DICOM standard. Each of the above-cited references is hereby incorporated by reference in their entireties. In one embodiment, the data store 182 also stores the user-defined display parameters associated with one or more of the images stored on the data store 182. As discussed in further detail below, the user-defined display parameters may vary depending of the type of image, area imaged, clinical indication, source of image, display device, user, or other factors. Accordingly, any type of user-defined display parameter is expressly contemplated for use in conjunction with the systems and methods described herein.

The exemplary image server 180 is configured to store images from multiple sources and in multiple formats. For example, the image server 180 may be configured to receive medical images in the DICOM format from multiple sources, store these images in the data store 182, and selectively transmit medical images to requesting computing devices.

The medical facility 190 may be a hospital, clinic, doctor's office, or any other medical facility. The medical facility 190 may include one or more imaging devices and may share medical images with the image server 180 or other authorized computing devices. In one embodiment, multiple computing systems, such as the computing system 100 may be housed at a medical facility, such as medical facility 190.

Definition of Terms

Below is a definition of certain terms used herein.

“Modality” is defined as a medical imaging device (a patient who undergoes an MRI is said to have been examined or scanned with the MRI modality).

“Medical image” is defined to include an image of an organism. It may include but is not limited to a radiograph, computed tomography (CT), magnetic resonance imaging (MRI), Ultrasound (US), mammogram, positron emission tomography scan (PET), nuclear scan (NM), pathology, endoscopy, ophthalmology, or many other types of medical images. While this description is directed to viewing and tracking of medical images, the methods and systems described herein may also be used in conjunction with non-medical images, such as, images of circuit boards, airplane wings, geologic mapping, and satellite images, for example.

“Patient” refers to an individual who undergoes a medical imaging examination.

“3D Imaging Volume” or “Imaging Volume” refers to the information acquired by an imaging device (also referred to as a “scanner”) in the form of images that together form a 3D volume of digital information representative of the volume that was scanned, such as a portion of a patient.

“Viewing” is defined to include the process of visually observing one or more medical images associated with exams.

“Viewer” is defined as any person who views a medical image.

“Reading” is defined to include the process of visually observing one or more medical images for the purpose of creating a professional medical report, also called an interpretation. When reading is complete, an exam may be labeled “read,” indicating that the medical professional has completed observation of the one or more medical images for purposes of creating a medical report.

“Reader” is defined to include one who is authorized to perform the reading process.

“User” is defined to include any person that is a viewer and/or a reader.

“Display parameters” are defined to include methods of display of an image or exam. For example, an image or exam may be displayed with a certain pixel window level or width (similar to brightness and contrast), in color, based on a certain color map, opacity map, or other display parameters.

“Full voxel display” is defined to include display on a monitor or other display system of information from every voxel of a 3D imaging volume.

“Full Resolution” is defined to include the concurrent display of all voxels of a 3D imaging volume.

“Reduced Resolution” is defined to include display of less than all of the voxels of a 3D imaging volume.

“User-defined display parameter” refers to rules that a user can establish and store in a database that establish criteria for image display that is considered adequate. For example, a user-defined display parameter might store a rule that triggers certain warnings or displays if all voxels have not been displayed or, alternatively, if at least a predetermined portion of the voxels have not been displayed with a certain display method (such as image window, level, brightness, contrast, opacity, color look-up table, or other parameters). User-defined display parameters may also refer to other image processing functions, such as edge enhancement and automated image analysis functions, e.g., computer-aided detection (CAD) techniques.

As noted above, some medical imaging scanners, such as computed tomography (CT) and Magnetic Resonance Imaging (MRI), are capable of collecting a series of adjacent 2D images through a region of interest that, when stacked up, represent a 3D imaging volume. In some cases, a three-dimensional volume is directly acquired. For example, each individual two-dimensional image might consist of 512×512 pixels (picture elements), with each pixel representing a 1 mm×1 mm×1 mm voxel (volume element) within the region scanned, although the dimensions of the voxel need not be equal. If 1,000 such contiguous images were acquired then these images would then form an imaging volume consisting of 512×512×1,000 voxels representing a volume of space that is 51.2 cm×51.2 cm×100 cm in size.

FIG. 2A is a three-dimensional depiction of an imaging volume 320 comprising a plurality of voxels 322. In the embodiment of FIG. 2A, a series of contiguous axial MRI images 310A-310N of a brain are stacked to yield the 3D imaging volume 320. In certain embodiments, the orientation of the scanned images with respect to the patient is arbitrary, as images from any orientation can be stacked to form a 3D imaging volume, such as imaging volume 320. Once an imaging volume is created, 2D images can be created in any plane through the imaging volume using, for example, a technique known as multiplanar reformatting. In the embodiment of FIG. 2B, two-dimensional images in the coronal orientation 330 may be generated from the imaging volume 320, even though the original 2D images 310 were collected in the axial plane. Thus, coronal images, such as coronal image 340 may be generated for viewing. The coronal image 340 comprises voxels from each of the source images 310A-310N at the predetermined plane. In one embodiment, images may be reformatted from any arbitrary oblique plane of the imaging volume 320. This is often useful to physicians interpreting imaging volumes as particular features of anatomy and pathology may be best appreciated in a particular imaging plane.

FIG. 3A is a CT image 410 of a patient's lumbar spine in the axial plane taken from an imaging volume comprising a plurality of axial images. FIG. 3B is a reformatted image 420 from the imaging volume in the sagittal plane. As those of skill in the art will appreciate, assessment of alignment of the vertebral bodies may be best appreciated in the sagittal plane. Accordingly, sagittal images, including image 420 may be created from the axial imaging volume using multiplanar reformatting. In the embodiment of FIG. 3A, the patient is rotated with respect to the scanner and, thus, creation of images that are in the true sagittal plane with respect to the patient's spine require that the images be reformatted along an oblique axis 430.

As described above, the process of multiplanar reformatting allows generation of reformatted images from imaging volumes in planes other than the plane in which the original images were acquired. Therefore, a viewer of an imaging volume may choose to view the source images acquired from the imaging device and/or reformatted images, reformatted to be in a plane that differs from the plane of the source images. No matter whether the viewer is viewing source images or reformatted images, it may be important that the viewer examines the entire imaging volume so that important features of the exam are appreciated. In addition, it may be important that voxels of the imaging volume are displayed according to a predefined set of display parameters.

FIG. 4 is a flowchart illustrating a method of tracking which voxels of a medical imaging exam have been displayed according to user-defined display parameters. More particularly, the exemplary method of FIG. 4 may be used to track which voxels of an imaging volume have been displayed by the physician, regardless of the plane of viewing, and provide feedback to the physician indicating whether the exam has been completely viewed. As noted above, it may be important and/or required that a user view all of a medical imaging volume at full resolution, or accordingly to other user-defined display parameters. The method described with reference to FIG. 4 is an example of one method of automatically tracking the portions of a 3D imaging volume, such as the voxels, that have already been displayed at full resolution, notating those portions, and providing the user with information indicating what portions of the imaging volume have been displayed at full resolution. This process is generally referred to as “voxel tracking.” In an advantageous embodiment, the user interface provides a real time status of what portions of the imaging volume have been displayed at full resolution, or according to other user-defined display parameters.

In one embodiment, the method described with respect to FIG. 4 is performed by a computing system 100, a medical facility 190, or an image server 180, for example. For ease of description, the method will be discussed below with reference to a computing system 100 performing the method. Depending on the embodiment, certain of the blocks described below may be removed, others may be added, and the sequence of the blocks may be altered.

In one embodiment, the user-defined display parameters specify that an entire medical imaging volume must be viewed at full resolution before a reader may mark the image as read. However, the user-defined display parameters may have different requirements, such as requiring that at least a defined portion of the voxels are displayed at full resolution and/or a defined portion of the voxels are viewed with a certain display method, for example. In another embodiment, the user-defined display parameters may specify that the imaging volume be viewed at a resolution that is less than full resolution. In other embodiments, the user-defined display parameters may specify additional display settings that must be satisfied in order to allow the reader to mark the imaging volume as read. For example, the display parameters may be set to require that every n^(th) voxel, or a certain percentage of the total voxels of an imaging volume, are displayed. Thus, various user-defined display parameters may be established on a user, modality, or facility basis, for example. In one embodiment, such as when viewing CT images, the display parameters may specify that the CT images are viewed using a specified series of display parameters, such as lung windows, bone windows, and/or other types of windows, for example. In this embodiment, if the user forgets to view the images separately using all the required display parameters, the CT images may be misinterpreted.

For ease of description, the following description refers to user-defined display parameters specifying that every voxel of the imaging volume is displayed at full resolution before it may be marked as read. However, the methods described herein are not limited to these display parameters and application of these methods using other user-defined display parameters is expressly contemplated. Any reference to tracking voxels at full resolution should be interpreted to cover similar systems and methods for monitoring and/or tracking of any other user-defined display parameter or combination of display parameters.

In one embodiment, the computing system 100 is configured to determine a portion of the imaging volume on which voxel tracking is to be applied. Many imaging volumes comprise regions outside the area of interest that are not important for a user, such as a doctor, to view and mark as read. For example, the imaging volume that results from a CT scan of the brain will include air outside of the head that is irrelevant to the analysis by the user. Accordingly, viewing of these irrelevant portions of the imaging volume according to the user-defined display parameters is not necessary. In one embodiment, the computing system 100 analyzes the medical image and determines those regions that are irrelevant to the user's analysis. These irrelevant regions are then excluded from the user-defined display parameters and a viewer may mark an image as read without viewing the irrelevant areas at full resolution, for example. In another embodiment, the user may define the irrelevant regions of an imaging volume prior to viewing portions of the image at full resolution. For example, the user may use the keyboard, mouse, or other input device, to select regions surrounding the volume of interest that do not require viewing according to the user-defined display parameters. In yet another embodiment, the user may determine that the relevant regions of an imaging volume have been viewed according to the display parameters, without the need to pre-select portions that should be viewed according to the display parameters. By providing for automatic and/or manual selection of irrelevant portions of a medical imaging volume, the viewer is not required to display those irrelevant portions of the medical imaging volume according to the user-defined display parameters, such as full resolution.

Returning to FIG. 4, in a block 210, a series of source images that make up an imaging volume are received from an image source. The image source may comprise one or more of the imaging devices 170, the image server 180, the medical facility 190, or any other device that is capable of transmitting medical images. The medical images may be received via the network 160, or by other means, such as transferred on a floppy disk, CD-ROM, or USB storage device. In certain embodiments, the received source images each comprise more pixels that the display device and, thus, an entire source image may not be concurrently displayed at full resolution. Commonly owned U.S. patent application Ser. No. 11/179,384 titled “Systems And Methods For Viewing Medical Images,” which is hereby incorporated by reference in its entirety, describes exemplary systems and methods of tracking portions of 2D images that have been displayed according to user-defined display parameters. Images of an imaging volume, either source images or reformatted images, may be tracked using the systems and methods described in that application so that relevant portions of each image are displayed according to the user-defined display parameters.

Continuing to a block 220, a plane through the imaging volume is selected for display on the display device. As discussed above, the source images of the imaging volume may not be of a plane that the viewer wishes to view. For example, as described above with respect to FIG. 3, detection of certain features or abnormalities in an imaging space may be more easily detectable in certain planes, which may not be the plane of the source images. Accordingly, in certain embodiments, the user may select a plane of view in which reformatted images will be generated and displayed. In one embodiment, reformatted images are generated using the process of multiplanar reformatting. However, other methods of reformatting portions of a 3D imaging space in order to form images from any plane of the imaging space may also be used in conjunction with the systems and methods described herein.

Moving to a block 230, at least a portion of one of images, e.g., source or reformatted images, is displayed on the display device. As noted above, in many embodiments, the source and reformatted images comprise more pixels than a display device is capable of displaying at full resolution. Accordingly, only a portion of the images may be concurrently displayed on the display device.

Moving to a block 240, the user can adjust the display characteristics of the image currently being viewed, for example by adjusting the window level and window width. In one embodiment, adjustments made to the display characteristics of the currently displayed image are made to other images of the imaging space. Accordingly, if a contrast, brightness, or color level, for example, of an image is adjusted, the remaining images in the imaging space may also be adjusted.

Continuing to a block 250, an indication of the portion of the imaging volume that is displayed at full resolution is recorded. For example, the voxels being displayed in the imaging plane may be recorded, such as by storing voxel information in a memory 130 of the computing system 100. Alternatively, the information regarding displayed voxels may be stored on a local mass storage device 120 or central server, such as the image server 180.

Moving to a block 260, an indication of which regions of the imaging volume have been displayed at full resolution is displayed. For example, the user might interactively create a series of reformatted coronal images from a set of axial images that make up the imaging volume. One or more display characteristics of a reference axial image that the user has chosen could be altered to reflect voxels within that image that have been displayed at full resolution in one or more imaging planes, as illustrated in FIG. 5. Multiple references images might be displayed, for example in axial, coronal and sagittal orientations, each displaying an indication of which voxels have been displayed at full resolution along the corresponding planes. Alternatively, a three-dimensional cube might be displayed, with regions on each of three displayed faces that illustrate what voxels have been displayed at full resolution along the corresponding plane. For example, a user interface may include visual indications as to which portions of an imaging volume have not been displayed, or which voxels have not been displayed using a user-defined display parameter, such as a specified window or level setting. In one embodiment, the computing system 100 automatically displays a message indicating which regions of the imaging volume have not displayed with full pixel display and/or meeting user-defined display parameter criteria. In another embodiment, the computing system 100 automatically directs the user to any regions of the imaging volume that have not been displayed at full resolution and/or meeting user-defined display parameter criteria.

In one embodiment, the adjustment of a display characteristic to indicate regions that have or have not been displayed at full resolution comprises changing a color of the image portion. In another embodiment, other indicators, such as lines surrounding those image portions already displayed at full resolution, may be used to discriminate between portions of the imaging volume that have been displayed at full resolution and portions that have not been displayed at full resolution. Based on the distinguishing display characteristic, the user may select for display a portion of the imaging volume that has not yet been displayed at full resolution. In one embodiment, coloring of the viewed voxels may be toggled on and off by the user. In another embodiment, a text message, icon, or other indication, may be displayed at the bottom of the display, for example, indicating that the imaging volume has been viewed according to the user-defined display parameters. In yet another embodiment, the outside margins of the viewing pane may change color or the system could beep or provide some other audible feedback when the imaging volume has been displayed according to the user-defined display parameters.

In a decision block 270, the computing system 100 determines if another plane of the imaging volume has been selected for display at full resolution. In one embodiment, the user is presented with a full or reduced resolution representation of certain images within the imaging volume, for example axial, coronal and sagittal images through the middle of the imaging volume. Selection of a plane to be displayed using multiplanar reformatting may be accomplished by pressing certain keys on a keyboard, such as the arrow keys, for example. In another embodiment, the user may change the selected portion for viewing by moving a mouse, or other input device. In another embodiment, the computing system 100 may be configured to periodically update the display with a plane of the imaging volume that has not yet been displayed at full resolution, or update the display in response to an input from the user.

If in the decision block 270, the computing device 100 determines that instructions have been received to display another portion of the imaging volume on the display device, the method returns to block 220 where the image plane to be displayed is selected. The method then repeats the steps 220, 230, 240, 250, 260, and 270, allowing the user to view various portions of the imaging space by viewing reformatted images from various planes, and tracking which voxels of the imaging space have been viewed by the user. Because information indicating which voxels of the imaging space have been displayed according to the user-defined display parameters is stored by the computing system, the user can advantageously track the portions of the image space that have been viewed.

Referring again to the decision block 270, if the computing device 100 determines that instructions to display another portion of the imaging volume have not been received, the method continues to a decision block 280, wherein the computing device 100 determines whether all of the voxels in the imaging volume have been displayed at full resolution. If it is determined that not all of the voxels in the imaging volume have been displayed at full resolution, the method continues to a block 290, wherein an indication, such as an audible or visual alert, is provided to the user that not all of the voxels in the imaging volume have been viewed at full resolution. The method then returns to block 220. In one embodiment, the computing system 100 automatically selects an image, either a source image or reformatted image, for display from the portion of the imaging space that have not yet been displayed at full resolution, and/or that have not been displayed such that user-defined display parameters have been met.

If, however, in the decision block 280, the computing device 100 determines that the entire image has been displayed at full resolution, the method continues to a block 285, wherein an indication, such as an audible or visual alert, is provided to the user that the entire imaging volume have been displayed at full resolution. In certain embodiments, the user is only able to mark the imaging volume as read when the method reaches block 285.

As noted above, the flowchart of FIG. 4 illustrates an exemplary process of tracking voxels viewed by a user according to exemplary user-defined display parameters. In particular, the user-defined display parameters in the example of FIG. 4 specify that the entire imaging volume is viewed at full resolution. However, in other embodiments the user-defined display parameters may require that, for example, only a portion of the imaging volume is displayed at full resolution, or any other predetermined reduced resolution. In one embodiment, the user or the software may select portions of the imaging volume that must be displayed according to the user-defined display parameters. In another embodiment, the display parameters may specify that the viewer determines when the imaging volume has been viewed according to the user-defined display parameters. In this embodiment, the system may track the viewed voxels of the imaging volume, present the viewer with a view of the imaging volume that distinguishes portions of the imaging volume that have not been viewed at full resolution, or according to any other user-defined display parameters, and the viewer can determine whether the image can be marked as read.

In one embodiment, the user can establish user-defined display parameters and store those parameters in a database. In certain embodiments, rules may be established and linked to an individual user, user type, exam type, modality, or system, for example. These rules may trigger voxel tracking when certain events occur, such as a particular user opens an imaging space for viewing. In certain embodiments, rules may designate that voxel tracking applies to only certain viewers or users. In one embodiment, one set of display parameters can apply to one modality and another set of display parameters can apply to another modality. In addition, the rules may include specific triggers or warnings that occur if the user-defined display parameters are not satisfied. In one embodiment, the rules may indicate that the computing system 100 automatically direct the user to any voxels that have not been displayed with specific user-defined display parameters when the user attempts to mark an imaging space as read.

In one embodiment, the user is not able to notate an imaging volume as being read, or completely viewed, until the entire imaging volume has been displayed at full resolution. Accordingly, in the exemplary method of FIG. 4, if not all of the imaging volume has been displayed at full resolution, the method indicates that the entire imaging volume has not been viewed at full resolution in block 290, and the method returns to block 220, wherein another portion of the imaging volume may be selected for viewing.

It is noted that medical imaging exams can be subclassified into exam types. For example, “CT of the Brain” or “MRI of the Knee” may be exam types. Exam types can also be grouped into exam groups. For example, a user using the computing system 100 can indicate that two different exam types, such as “CT of the Chest” and “MRI of the Chest” belong in the same exam group, or that “CT of the Chest” and “CT of the Abdomen” belong in the same group. A user can also, via the system 100, set up rules related to voxel tracking that are linked to the exam group and/or modality and/or exam type or even per other exam specifiers. Thus, a user may require that all exams of a certain type or group are tracked according to user-defined rules, e.g., to determine if every voxel is displayed, and/or if every voxel is displayed with a bone window setting, etc. The rules can also be applied under other user-defined conditions, e.g., the referring doctor is an oncologist or if the exam indications are for cancer evaluation.

Similarly, users can also be grouped into user roles or user groups. A particular user or user having a user role may: (1) require a warning if the specified voxel tracking rules are not met (but still allow the user to mark the exam as “read”), (2) require that the rules are met before the exam is marked as “read”, and\or (3) display a warning or track displayed data even if the user does not have the right to mark the exam as “read.” The computing system 100 may also provide users guidance information. Voxel tracking might also be useful for a researcher or administrator who is studying the behavior of reading or viewing health care professionals.

FIG. 5 illustrates portions of an exemplary graphical user interface (GUI) that may be displayed on a display device, either concurrently or separately. More particularly, the exemplary GUI may display a reference image 510 that allows the user to select an image plane for viewing using the user-defined display parameters. In the embodiment of FIG. 5, the reference image 510 comprises a brain CT. A navigation line 520 may be adjusted by the user in order to move to another imaging plane. In one embodiment, as the user moves the navigation line, such as by using a mouse connected to the computing system 100, the computing system 100 generates 2D images perpendicular to the navigation line 520 using MPR (multiplanar reformatting), e.g., in the coronal orientation. The reformatted image 540 corresponding to the navigation line 520 is displayed in another portion of the GUI or, alternatively, may replace the navigation image 510. In one embodiment, the navigation image 510 is displayed in a pane of the GUI that is smaller than a pane that displays a corresponding reformatted image. In another embodiment, the navigational image 510 may be alternatively displayed on the display device so that more of the images may be concurrently displayed, for example. In the embodiment of FIG. 5, a contrast inverted region 530 of the navigation image 510 indicates the portions of the imaging volume that have been displayed according to the user-defined display parameters, such as full pixel resolution. Thus, the user can determine which portions of the imaging volume have been viewed according to the user-defined display parameters by noting the portions of the navigation image 510 that is within the inverted region 530. As noted above, other methods of indicating portions of the imaging space that have been displayed may also be used.

FIG. 6 illustrates a display device 610 displaying the navigation image 510 and the reformatted image 540. As noted above, the reformatted image 540 is a cross-section of the imaging space at the location of the navigation line 520 on the navigation image 510. In the embodiment of FIG. 6, as the user moves the navigation line 520 up and down the navigation image 510, the reformatted image 540 is replaced with other reformatted images corresponding to the current location of the navigation line 520. In this embodiment, the user can see which portions of the imaging volume have already been viewed while viewing portions of the imaging volume in another plane. In other embodiments, the navigation line 520 is oriented vertically, or at any other orientation, so that the user may cause generation of reformatted images in any plane desirable.

In another embodiment, multiple navigation images may be displayed on the display device 610. For example, two navigation images comprising orthogonal planes of the imaging volume may be concurrently displayed on the display device 610 and may provide the viewer with additional information regarding the location of the reformatted images displayed on the display device 610. In other embodiments, three or more navigation images from different planes of the imaging volume may be concurrently, or alternatively, displayed on the display device 610.

The foregoing description details certain embodiments of the invention. It will be appreciated, however, that no matter how detailed the foregoing appears in text, the invention can be practiced in many ways. For example, the above-described pixel checking method may be performed on other types of images, in addition to medical images. For example, images of circuit boards, airplane wings, geology, and satellite imagery may be analyzed using the described systems and methods for monitoring whether a three dimensional imaging volume has been viewed according to predefined display parameters. As is also stated above, it should be noted that the use of particular terminology when describing certain features or aspects of the invention should not be taken to imply that the terminology is being re-defined herein to be restricted to including any specific characteristics of the features or aspects of the invention with which that terminology is associated. The scope of the invention should therefore be construed in accordance with the appended claims and any equivalents thereof. 

What is claimed is:
 1. A computing system comprising: a computer readable storage medium having program instructions embodied therewith; and one or more processors configured to execute the program instructions to cause the one or more processors to: determine, for a three dimensional imaging volume comprising a plurality of voxels, a subset of voxels from the plurality of voxels to be displayed, wherein the subset of voxels is represented as at least one of: a particular percentage of the plurality of voxels are to be displayed, or particular portions of the plurality of voxels are to be displayed, and wherein the subset of voxels is based on one or more of: a resolution of the three dimensional imaging volume, a user of the computing system, a type of user of the computing system, a modality of the three dimensional imaging volume, an exam type associated with the three dimensional imaging volume, a group of exams of which the three dimensional imaging volume is a part, a group of users of the computing system of which the user is a member, a facility in which the three dimensional imaging volume is displayed, or a system on which the three dimensional imaging volume is displayed; receive indications of portions of the three dimensional imaging volume that are selectively displayed; and determine whether the subset of voxels has been displayed based on the indications of portions of the three dimensional image volume that have been selectively displayed.
 2. The computing system of claim 1, wherein the subset of voxels is based on a user the three dimensional imaging volume is displayed to.
 3. The computing system of claim 1, wherein the subset of voxels is based on an exam type associated with the three dimensional imaging volume.
 4. The computing system of claim 1, wherein the one or more processors are configured to execute the program instructions to further cause the one or more processors to: in response to determining that the subset of voxels has not been displayed based on the indications of portions of the three dimensional imaging volume that have been selectively displayed, provide a warning to a user.
 5. A computer-implemented method comprising: by one or more processors executing program instructions: determining, for a three dimensional imaging volume comprising a plurality of voxels, a subset of voxels from the plurality of voxels to be displayed, wherein the subset of voxels is represented as at least one of: a particular percentage of the plurality of voxels are to be displayed, or particular portions of the plurality of voxels are to be displayed, and wherein the subset of voxels is based on one or more of: a resolution of the three dimensional imaging volume, a user of the computing system, a type of user of the computing system, a modality of the three dimensional imaging volume, an exam type associated with the three dimensional imaging volume, a group of exams of which the three dimensional imaging volume is a part, a group of users of the computing system of which the user is a member, a facility in which the three dimensional imaging volume is displayed, or a system on which the three dimensional imaging volume is displayed; receiving indications of portions of the three dimensional imaging volume that are selectively displayed; and determining whether the subset of voxels has been displayed based on the indication of portions of the three dimensional imaging volume that have been selectively displayed.
 6. The computer-implemented method of claim 5, wherein the subset of voxels is based on a user the three dimensional imaging volume is displayed to.
 7. The computer-implemented method of claim 5, wherein the subset of voxels is based on an exam type associated with the three dimensional imaging volume.
 8. The computer-implemented method of claim 5 further comprising: by the one or more processors executing program instructions: in response to determining that the subset of voxels has not been displayed based on the indications of portions of the three dimensional imaging volume that have been selectively displayed, providing a warning to a user.
 9. A computer program product comprising a non-transitory computer readable storage medium having program instructions embodied therewith, the program instructions executable by one or more processors to cause the one or more processors to: determine, for a three dimensional imaging volume comprising a plurality of voxels, a subset of voxels from the plurality of voxels to be displayed, wherein the subset of voxels is represented as at least one of: a particular percentage of the plurality of voxels are to be displayed, or particular portions of the plurality of voxels are to be displayed, and wherein the subset of voxels is based on one or more of: a resolution of the three dimensional imaging volume, a user of the computing system, a type of user of the computing system, a modality of the three dimensional imaging volume, an exam type associated with the three dimensional imaging volume, a group of exams of which the three dimensional imaging volume is a part, a group of users of the computing system of which the user is a member, a facility in which the three dimensional imaging volume is displayed, or a system on which the three dimensional imaging volume is displayed; receive indications of portions of the three dimensional imaging volume that are selectively displayed; and determine whether the subset of voxels has been displayed based on the indications of the portions of three dimensional imaging volume that have been selectively displayed.
 10. The computer program product of claim 9, wherein the subset of voxels is based on a user the three dimensional imaging volume is displayed to.
 11. The computer program product of claim 9, wherein the subset of voxels is based on an exam type associated with the three dimensional imaging volume.
 12. The computer program product of claim 9, wherein the program instructions are executable by one or more processors to further cause the one or more processors to: in response to determining that the subset of voxels has not been displayed based on the indications of portions of the three dimensional imaging volume that have been selectively displayed, providing a warning to a user. 